Solar Impulse plane

Credit: Getty Images

MOUNTAIN VIEW, CA - MAY 03: Pilot Bertrand Piccard waves goodbye before taking off in the Solar Impulse solar electric airplane at Moffett Field on May 3, 2013 in Mountain View, California. Pilots Bertrand Piccard and Andre Borschberg are attempting the first cross-continental flight in a solar powered plane that can travel day and night. (Photo by Beck Diefenbach/Getty Images)